Ultrasonic beam shaping device



Oct. 27, 1953 J. c. SMACK ULTRASONIC BEAM SHAPING DEVICE Filed June 15, 1950 FIG. 3

FIG. l

FIG. 4

/5 INVENTOR.

JOHN c. sMAcK FIG. 2 w

ATTORNEY Patented Oct. 27, 1953 ULTRASONIC BEAM SHAPING: DEVICE John C. Smack, White Plains, N. Y., assignor to Sperry Products, Inc., Danhury, Conm, a corporation of New York Application June 15, 1950, Serial. No. 168,335

(01. filth-8.3.).

3. Claims. 1

This invention relates to a method and means for obtaining ultrasonic beams of vibrational waves of any desired cross-sectional outline, where such beams cannot readily be obtained directly from a piezo-electric element in the form of a quartz crystal. The manufacture of such crystals is characterized by definite limitations as to size and shape of crystals, and hence definite limitations as to size and shape of the ultrasonic beam generated by such crystals. It is a particularly difficult problem to devise crystals-which will generate a narrow beam, a pencil-like beam of small cross-sectional area, or a beam of any other desired section contour. It is therefore one of the principal objects of this invention to provide a method and means for obtaining beams of the type which has heretofore been difiicult to generate, particularly beams having the dimension in one or both directions relatively narrow.

It is a further object to obtain the result described above with the use of crystals of standard dimensions which do not require special processing or adaptation for this purpose.

Further objects and advantages of this invention will become apparent in the following detailed description thereof.

In the accompanying drawings,

Fig. 1 is a front elevation of one embodiment of my invention.

Fig. 2 is a plan view of the Fig. 1 device.

Fig. 3 is a front elevation of another embodiment of my invention.

Fig. 4 is a plan view of the Fig. 3 device.

Fig. 5 is an isometric projection of the Fig. 1 device.

Fig. 6 is a front elevation of a form of my invention applied to an angle beam.

Fig. '7 is a side elevation of the Fig. 6 device.

Referring first to Fig. 1, there is shown a crystal l whose upper and lower surfaces may be provided with conductive material to which connections II and I2 may be made, said connections leading to a suitable source of electric oscillations (not shown). The crystal transforms the electric oscillations into mechanical vibrations which it is desired to transmit into an object I for a purpose such as the internal inspection of the object for discontinuities.

The crystal shown is of conventional shape and size of a type which is readily manufactured by known methods. Such methods do not permit the production of crystals designed to transmit a beam of certain desired cross-sectional outlines particularly not when the desired beam has one or both dimensions relatively small to yield a narrow beam, a-nencil beam, or a beam of any desired cross-sectional contour. Nevertheless it. is found highly desirable to employ such beams of special cross-sectional outline for the testing or inspection of particular types of objects. By this invention I obtain such specially shaped beams from a standard sized crystal manufactured by standard methods.

To accomplish the above results, I employ an intermediate member interposed between the crystal [0 and the object l5. The member 23 is made of material having high conductivity for ultrasonic vibrations, examples of such material being methyl methacrylate or other plastics, and

metals such as aluminum and steel. The member 22) would ordinarily transmit to object 15 a beam whose cross-section had substantially the same outline as the crystal. However, by the following method I can obtain a beam of any desired outline, within the limits of the crystal area. For this purpose, I provide in member 20 one or more slots 25, 25'. The plane of these slots is such as to intercept the generated beam, and in Figs. 1 to 4 is shown as substantially transverse to the direction of transmission of the ultrasonic beam. Since the slot provides an air gap of high attenuating properties, it will be apparent that the portion of the generated beam intercepted by the slots will not be transmitted into object l5 but will be absorbed in the slots. Thus in Figs. 1 and 2 a rectangular solid portion remains uncut in member 20 and will therefore transmit a rectangular beam of vibrational waves into object l5. If portion is additionally slotted in a direction at right angles to slots 25, 25' in the plane of these slots, there will remain unslotted only a small pencil-like post 3| (see Figs. 3 and 4) in member 20 to transmit a pencil-like beam of vibrational waves into object [5. Thus by suitably slotting the intermediate member 20, a beam having any desired outline within the area of crystal I0 may be obtained.

The invention is shown in Figs. 1 to 4 as applied to a system for transmitting vibrational waves in a direction normal to the entering surface of object l5. In Figs. 6 and '7 there is disclosed how the invention may be applied to the transmission of vibrational waves into the object at an angle to the entering surface. For this purpose the intermediate member 20 may be provided with a surface 40 inclined at an angle to the entering surface of object I5. Crystal l0 engages the inclined surface. Slots 25, 25' are provided as before in a plane designed to intercept the generated beam over a predetermined area to yield a a beam 4| of desired cross-sectional outline which then enters object [5 at the given angle of inclination.

The slots may be sealed against the entry of fluid or other substance which may reduce its attenuating properties. This will permit the device to be used in applications where it is necessary to submerge it in a liquid.

While the foregoing description of the invention has been directed to the transmission of ultrasonic beams of predetermined cross-sectional contour, it will be apparent that the invention will operate just as well to limit the reception of ultrasonic beams to the desired cross-sectional contour. Thus in through transmission from a crystal transmitter to a crystal receiver through a fluid medium there are many reflected and stray vibrational waves which it is desirable to exclude from the receiver. By suitably shaping the uncut section of intermediate member 20 any desired waves may be received and others excluded.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. A device for use with a piezo-electric crystal in the transmission and reception of ultrasonic vibrational waves in an object, comprising a wavetransmitting member having one surface in engagement with one surface of the crystal and having its other surface in engagement with the object, said member being slotted in a direction to intercept the vibrations to render a predetermined portion of the member substantially non-conductive to the ultrasonic vibrations.

2. A device for use with a piezo-electric crystal in the transmission and reception of ultrasonic vibrational waves in an object, comprising a wave transmitting member having one surface in engagement with one surface of the crystal and having its other surface in engagement with the object, said member being slotted in a direction substantially transverse to the direction of propagation of the ultrasonic vibrations to render a predetermined portion of the member substantially non-conductive to the ultrasonic vibrations.

3. A device for use with a piezo-electric crystal in the transmission and reception of ultrasonic vibrational waves in an object, comprising a Wavetransmitting member having one surface in engagement with one surface of the crystal and having its other surface in engagement with the object, said member being slotted in a direction substantially transverse to the direction of propagation of the ultrasonic vibrations to render a predetermined portion of the cross-sectional area of the member substantially non-conductive to the ultrasonic vibrations.

JOHN C. SMACK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,164,125 Sokoloff June 27, 1939 2,164,638 Broeze July 4, 1939 2,374,637 Hayes Apr. 24, 1945 2,405,187 Beniofif Aug. 6, 1946 2,433,383 Mason Dec. 30, 1947 2,448,352 Carlin Aug. 31, 1948 2,467,301 Firestone Apr. 12, 1949 2,505,867 Meunier May 2, 1950 2,512,743 Hansell June 27, 1950 

